Recent Developments in Olefin Cross‐Metathesis

Abstract

Among the many types of transition-metal-catalyzed C-C bond-forming reactions, olefin metathesis has come to the fore in recent years owing to the wide range of transformations that are possible with commercially available and easily handled catalysts. Consequently, olefin metathesis is now widely considered as one of the most powerful synthetic tools in organic chemistry. Until recently the intermolecular variant of this reaction, cross-metathesis, had been neglected despite its potential. With the evolution of new catalysts, the selectivity, efficiency, and functional-group compatibility of this reaction have improved to a level that was unimaginable just a few years ago. These advances, together with a better understanding of the mechanism and catalyst-substrate interactions, have brought us to a stage where more and more researchers are employing cross-metathesis reactions in multistep procedures and in the synthesis of natural products. The recent inclusion of alkynes and hindered bicyclic olefins as viable substrates for bimolecular metathesis coupling, the discovery of enantioselective cross-metathesis and cross-metathesis in water, and the successful marriage of metathesis and solid-phase organic synthesis has further widened the scope of this versatile reaction.

First FT-Raman and 1H NMR comparative investigations in ring opening metathesis polymerization

“…Within this category olefin metathesis (mainly as ringclosing metathesis, cross-metathesis and ring-opening metathesis polymerization (ROMP)), has won a leading position owing to its success in yielding various natural products, specialty polymers, pharmaceuticals and otherwise hard-to-get organic compounds [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Where organometallics and dendrimers merge: the incorporation of organometallic species into dendritic molecules

“…Undoubtedly, olefin metathesis [56], with either ruthenium [57] or molybdenum [58] catalyst systems, is one of the more important reactions in polymer chemistry and natural product synthesis [59] and the ability to recover and reuse the catalysts would greatly impact the cost efficiency of these reactions. A simple dendrimer containing four active Ru sites was reported.…”

Diene, Enyne, and Diyne Metathesis in Natural Product Synthesis

“…Both types of compounds are now routinely prepared by RCM, either via path A or via path B in Fig. 6.Additionally, chiral lactones II can be used to induce stereospecificity to the neighboring carbons via substrate-controlled reactions, as illustrated by the transformation IIAEIV or IIAEV in the scheme.While the formation of pentenolides by RCM of acrylates (path A) mediated by Grubbs' first-generation catalyst A often proceeded sluggishly, needing Ti(OiPr) 4 as an additive in many cases, the ring closure occurs generally without problems in the presence of second-generation catalysts C, D, and E. Disubstituted dihydropyrans of the type VIII are prepared preferably via path B, by RCM of mixed acrolein acetals VI, rather than via the corresponding lactones II, as the former cyclize uneventfully with catalyst A.…”

“…Many general reviews on metathesis reactions in organic synthesis [1] and catalyst development [2] have appeared during the past 5 years, including the most recent contributions concerning enyne metathesis [3], olefin cross metathesis [4], and alkyne metathesis in natural product synthesis [5]. A number of reviews have focused on special applications in organic synthesis, such as olefin metathesis in carbohydrate chemistry [6], RCM leading to medium-sized rings [7] or to heterocycles, alkaloids, and peptidomimetics [8], macrocyclizations leading to (E) double bonds [9], RCM in the synthesis of epothilones and polyether natural products [10], and in the total synthesis of laulimalide [11].…”